1.225 V fixed shunt reference — the BOM-fit anchor
The Texas Instruments LM4041DEM3X-1.2/NOPB is a precision shunt voltage reference delivering a fixed 1.225 V output with ±1% initial tolerance. It belongs to the LM4041 family of low-power shunt references, designed for applications where a stable, accurate voltage rail is needed without the dropout overhead of a series regulator.
73 µA cathode current — low-power analog bias
The minimum cathode current is 73 µA, which means the reference can be biased with a single resistor from a higher supply rail while drawing negligible overhead. This suits battery-powered instrumentation and always-on ADC reference circuits where every microamp counts.
12 mA output, 150 ppm/°C — the load and drift envelope
Output current capability is 12 mA, enough to bias multiple ADC inputs or pull-up networks without an external buffer.
20 µVrms noise — clean rail for precision converters
Wideband noise is specified at 20 µVrms over the 10 Hz to 10 kHz band. This is low enough for a 12-bit SAR ADC reference without additional filtering, though a 100 nF bypass cap at the output pin is still recommended per standard practice.